Glucocorticoid status-dependent changes in tyrosine aminotransferase and tryptophan oxygenase activity in the rat liver and thymus
1998
Koricanac, G. | Vulovic, M. | Kanazir, D.T. | Ribarac-Stepic, N. ("Vinca" Institute of Nuclear Sciences, Belgrade (Yugoslavia). Laboratory of Molecular Biology and Endocrinology)
The effects of adrenalectomy and/or dexamethasone treatment on tryptophan oxygenase (TO; EC 2.6.1.5) and tyrosine aminotransferase (TAT; EC 1.13.1.12) activity 2 h and 18 h after hormone treatment have been investigated in rat liver and thymus. The induction of these enzymes was the highest at these time intervals after the applied dose (5 mg/kg b.w.) of dexamethasone. The obtained results indicate that dexamethasone treatment is followed by induction of tyrosine aminotransferase and tryptophan oxygenase activities in liver but only tyrosine aminotransferase activity in thymus. The induction of enzyme activity was observed in either intact or adrenalectomized animals treated by hormone. The effects of dexamethasone treatment were observed 2 h and 18 h after hormone administration in comparison with appropriate saline injected controls which were nonoperated or sham operated. Tyrosine aminotransferase activity in both analyzed tissues and tryptophan oxygenase only in the liver were decreased three days after adrenalectomy. The activity of tryptophan oxygenase in thymus tissue was not detected by means of widely applied method for analysis of this enzyme in other related studies.
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